Itanagar, May 2 (IANS): Indian authorities Monday zeroed in on three probable locations to track down the helicopter carrying Arunachal Pradesh Chief Minister Dorjee Khandu that went missing two days ago along the India-Bhutan border, officials said.

According to a senior official of the Crisis Management Team monitoring the rescue and search operation here, the three locations are Eaglenest Wildlife Sanctuary and Nagajen in the state's West Kameng district, and the small village of Mobi in Trashiyangtse district of Bhutan.

All the three locations are bordering Tawang district of Arunachal Pradesh from where the Pawan Hans AS350 B-3 helicopter carrying the chief minister and four others went missing after it took off from Tawang at 9.50 a.m. Saturday.

The last radio contact with the ground was about 20 minutes after take-off as it flew over the Sela Pass along the Chinese border perched at an altitude of 13,700 feet.

"The search teams are now concentrating on the three areas to locate the helicopter. The three locations were zeroed in based on satellite images and other local reports," the official told IANS requesting anonymity.

Meanwhile, four Indian Air Force helicopters were pressed into service early Monday for conducting aerial surveys - two Mi-17 helicopters took off from Tawang and two Cheetak helicopters flew from a base in Tezpur in Assam.

Bad weather, however, is hampering the operation. Aerial operations were abandoned Sunday following heavy rains in the northeastern state of Arunachal Pradesh.

"There is no news of the missing helicopter. Search operations are on with hundreds of army, police, and paramilitary troopers conducting an intensive ground search along the route the helicopter flew. Besides a coordinated operation is also on in Bhutan," said senior minister Nabam Tuki.

On Sunday, two satellites from the Indian Space Research Organisation (ISRO) had taken images but they came out hazy due to bad weather.

Two Sukhoi-30 aircrafts from a base in Bareilly also completed aerial mapping over Arunachal Pradesh Sunday in an attempt to get definite clues about the missing helicopter.

"We are expecting a report of the satellite images later in the day," the minister said.

A sense of despondency prevails in Arunachal Pradesh.

"We are hoping against hope to get some news about the helicopter and its occupants. There are prayers being held in all the Buddhist monasteries," said Congress legislator from Tawang Tsewang Dhondup.

Yeshmi Lamu, the lone woman occupant in the helicopter is the younger sister of Dhondhup.

"She was in the helicopter with the chief minister for some medical check-up in Itanagar."

"Everybody is praying for the chief minister and the other four people. We also want a clarification from the governor for making such an irresponsible statement about the safe landing of the helicopter," said Baman Felix, a civil rights leader in Arunachal Pradesh.

Arunachal Pradesh Governor had Saturday said the chopper had safely landed -- a statement that turned out to be false.

The helicopter in question, AS350 B-3, is a single-engine chopper. In case of an engine failure, there are very slim chances of the helicopter making a safe landing.

The incident comes just days after a Pawan Hans helicopter crashed in Tawang April 19, killing 17 people and injuring six.

The Pawan Hans Helicopter Services Limited (PHHL) has been operating five helicopters across Arunachal Pradesh, Sikkim, Meghalaya, Nagaland and Tripura and daily Guwahati-Tawang services for the past nine years. It is one of the major lifelines of landlocked Arunachal Pradesh.